System and methods for directional steering of electrical stimulation

ABSTRACT

Method and systems for determining a set of stimulation parameters for an implantable stimulation device include performing the following steps or actions: receiving a stimulation target; determining a target stimulation field based on the stimulation target; receiving a weighting for a plurality of spatial regions defined relative to a lead including a plurality of electrodes, where a weighting for at least one of the spatial regions is different from a weighting for another one of the spatial regions; and determining, using the weightings for the plurality of spatial regions, a set of stimulation parameters to produce a generated stimulation field that approximates the target stimulation field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application Ser. No. 62/327,296, filed Apr. 25, 2016,which is incorporated herein by reference.

FIELD

The invention is directed to the area of electrical stimulation systemsand leads and methods of making and using the systems and leads. Thepresent invention is also directed to systems and methods fordirectional steering of electrical stimulation, as well as methods ofmaking and using systems.

BACKGROUND

Electrical stimulation can be useful for treating a variety ofconditions. Deep brain stimulation can be useful for treating, forexample, Parkinson's disease, dystonia, essential tremor, chronic pain,Huntington's disease, levodopa-induced dyskinesias and rigidity,bradykinesia, epilepsy and seizures, eating disorders, and mooddisorders. Typically, a lead with a stimulating electrode at or near atip of the lead provides the stimulation to target neurons in the brain.Magnetic resonance imaging (“MRI”) or computerized tomography (“CT”)scans can provide a starting point for determining where the stimulatingelectrode should be positioned to provide the desired stimulus to thetarget neurons.

After the lead is implanted into a patient's brain, electrical stimuluscurrent can be delivered through selected electrodes on the lead tostimulate target neurons in the brain. The electrodes can be formed intorings or segments disposed on a distal portion of the lead. The stimuluscurrent projects from the electrodes. Using segmented electrodes canprovide directionality to the stimulus current and permit a clinician tosteer the current to a desired direction and stimulation field.

BRIEF SUMMARY

One embodiment is a computer-implemented method for determining a set ofstimulation parameters for an implantable stimulation device, the methodincluding: receiving, by a computer processor, a stimulation target;determining, by the computer processor, a target stimulation field basedon the stimulation target; receiving, by the computer processor, aweighting for a plurality of spatial regions defined relative to a leadincluding a plurality of electrodes, where a weighting for at least oneof the spatial regions is different from a weighting for another one ofthe spatial regions; and determining, by the computer processor andusing the weightings for the plurality of spatial regions, a set ofstimulation parameters to produce a generated stimulation field thatapproximates the target stimulation field.

Another embodiment is a non-transitory computer-readable medium havingprocessor-executable instructions for determining a set of stimulationparameters, the processor-executable instructions when installed onto adevice enable the device to perform actions, including: receive astimulation target; determine a target stimulation field based on thestimulation target; receive a weighting for a plurality of spatialregions defined relative to a lead including a plurality of electrodes,where a weighting for at least one of the spatial regions is differentfrom a weighting for another one of the spatial regions; and determine,using the weightings for the plurality of spatial regions, a set ofstimulation parameters to produce a generated stimulation field thatapproximates the target stimulation field.

Yet another embodiment is a system for determining a set of stimulationparameters, the system including: a display; and a computer processorcoupled to the display and configured and arranged to perform thefollowing actions: receive a stimulation target; determine a targetstimulation field based on the stimulation target; receive a weightingfor a plurality of spatial regions defined relative to a lead includinga plurality of electrodes, where a weighting for at least one of thespatial regions is different from a weighting for another one of thespatial regions; and determine, using the weightings for the pluralityof spatial regions, a set of stimulation parameters to produce agenerated stimulation field that approximates the target stimulationfield. In at least some embodiments, the system further includes animplantable lead and an implantable control module coupleable to thelead and configured and arranged to receive the set of stimulationparameters from the computer processor and to deliver electricalstimulation to a patient using the lead according to the set ofstimulation parameters.

In at least some embodiments, the method or actions further includetransmitting the set of stimulation parameters for reception by animplantable stimulation device for delivery of electrical stimulation toa patient. In at least some embodiments, a default weighting is assignedto each spatial region absent user selection of the weighting for thatspatial region.

In at least some embodiments, the stimulation target is a center ofstimulation or a virtual electrode. In at least some embodiments,receiving a stimulation target includes receiving a drawing of thevirtual electrode on a representation of the lead.

In at least some embodiments, the steps or actions of receiving astimulation target and determining a target stimulation field togetherinclude receiving a user-defined target stimulation field. In at leastsome embodiments, receiving a user-defined target stimulation fieldincludes receiving a drawing of the user-defined target stimulationfield relative to a representation of the lead.

In at least some embodiments, the method or actions further includereceiving a user-definition of at least one of the spatial regionsrelative to a representation of the implanted lead. In at least someembodiments, determining, using the weightings for the plurality ofspatial regions, a set of stimulation parameters includes minimizing aweighted error between the generated stimulation field and the targetstimulation field using the weightings for the spatial regions. In atleast some embodiments, the method or actions further include receivinga selection of a model for determining the weighted error. In at leastsome embodiments, the method or actions further include displaying thetarget stimulation field and the generated stimulation field.

In at least some embodiments, the method or actions further includereceiving, by the computer processor, a setting of at least one of theelectrodes to a zero stimulation amplitude prior to the determining ofthe set of stimulation parameters and requiring, during thedetermination of the set of stimulation parameters, that the at leastone of the electrodes set to the zero stimulation amplitude remains atthe zero stimulation amplitude. In at least some embodiments, the methodor actions further include upon receiving the setting of the at leastone of the electrodes to a zero amplitude, presenting a menu ofuser-selectable reasons for the setting.

In at least some embodiments, the method or actions further includereceiving, by the computer processor, a setting of at least one of theelectrodes to a fixed stimulation amplitude prior to the determining ofthe set of stimulation parameters and requiring, during thedetermination of the set of stimulation parameters, that the at leastone of the electrodes set to the fixed stimulation amplitude remains atthe fixed stimulation amplitude.

In at least some embodiments, the weighting for user selection is aqualitative, non-numerical description of the weighting. In at leastsome embodiments, the spatial regions are pre-defined. In at least someembodiments, the spatial regions include at least one close region, atleast one medial region, and at least one far region, where the at leastone close region is defined nearer the lead than the at least one medialregion which, in turn, is defined nearer the lead than the at least onefar region.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

For a better understanding of the present invention, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, wherein:

FIG. 1 is a schematic side view of one embodiment of a device for brainstimulation, according to the invention;

FIG. 2 is a schematic diagram of radial current steering along variouselectrode levels along the length of a lead, according to the invention;

FIG. 3A is a perspective view of an embodiment of a portion of a leadhaving a plurality of segmented electrodes, according to the invention;

FIG. 3B is a perspective view of a second embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3C is a perspective view of a third embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3D is a perspective view of a fourth embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3E is a perspective view of a fifth embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3F is a perspective view of a sixth embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3G is a perspective view of a seventh embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 3H is a perspective view of an eighth embodiment of a portion of alead having a plurality of segmented electrodes, according to theinvention;

FIG. 4 is a schematic flowchart of one embodiment of a method ofdetermining a set of stimulation parameters, according to the invention;

FIG. 5A is a schematic illustration of one embodiment of an interfaceillustrating a distal end of a lead and a selected virtual electrode,according to the invention;

FIG. 5B is a schematic illustration of one embodiment of an interfaceillustrating a lateral cross-section of a distal end of a lead and aselected virtual electrode, according to the invention;

FIG. 6A is a schematic illustration of one embodiment of an interfaceillustrating multiple spatial regions (with a portion of the model ofthe lead obscured to better illustrate the spatial regions), accordingto the invention;

FIG. 6B is a schematic illustration of the interface of 6A with oneexample of a selection of weightings for the spatial regions, accordingto the invention;

FIG. 6C is a schematic illustration of the interface of 6A with anotherexample of a selection of weightings for the spatial regions, accordingto the invention;

FIG. 7 is a schematic illustration of one model for determining aweighted error using a grid of points with a same number of points ineach spatial region, according to the invention;

FIG. 8 is a schematic illustration of another model for determining aweighted error using a grid of points with a number of points in eachspatial region depending on the weighting, according to the invention;

FIG. 9 is a schematic illustration of one embodiment of an interfaceillustrating setting of an electrode to a zero amplitude, according tothe invention;

FIG. 10 is a schematic illustration of one embodiment of an interfaceillustrating setting of an electrode to a fixed amplitude, according tothe invention; and

FIG. 11 is a schematic illustration of one embodiment of a system forpracticing the invention.

DETAILED DESCRIPTION

The invention is directed to the area of electrical stimulation systemsand leads and methods of making and using the systems and leads. Thepresent invention is also directed to systems and methods fordirectional steering of electrical stimulation, as well as methods ofmaking and using systems.

A lead for deep brain stimulation can include stimulation electrodes,recording electrodes, or a combination of both. At least some of thestimulation electrodes, recording electrodes, or both are provided inthe form of segmented electrodes that extend only partially around thecircumference of the lead. These segmented electrodes can be provided insets of electrodes, with each set having electrodes radially distributedabout the lead at a particular longitudinal position. For illustrativepurposes, the leads are described herein relative to use for deep brainstimulation, but it will be understood that any of the leads can be usedfor applications other than deep brain stimulation, including spinalcord stimulation, peripheral nerve stimulation, or stimulation of othernerves and tissues.

Suitable implantable electrical stimulation systems include, but are notlimited to, a least one lead with one or more electrodes disposed on adistal end of the lead and one or more terminals disposed on one or moreproximal ends of the lead. Leads include, for example, percutaneousleads. Examples of electrical stimulation systems with leads are foundin, for example, U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029;6,609,032; 6,741,892; 7,244,150; 7,450,997; 7,672,734; 7,761,165;7,783,359; 7,792,590; 7,809,446; 7,949,395; 7,974,706; 8,175,710;8,224,450; 8,271,094; 8,295,944; 8,364,278; 8,391,985; and 8,688,235;and U.S. Patent Applications Publication Nos. 2007/0150036;2009/0187222; 2009/0276021; 2010/0076535; 2010/0268298; 2011/0005069;2011/0004267; 2011/0078900; 2011/0130817; 2011/0130818; 2011/0238129;2011/0313500; 2012/0016378; 2012/0046710; 2012/0071949; 2012/0165911;2012/0197375; 2012/0203316; 2012/0203320; 2012/0203321; 2012/0316615;2013/0105071; and 2013/0197602, all of which are incorporated byreference.

In at least some embodiments, a practitioner may determine the positionof the target neurons using recording electrode(s) and then position thestimulation electrode(s) accordingly. In some embodiments, the sameelectrodes can be used for both recording and stimulation. In someembodiments, separate leads can be used; one with recording electrodeswhich identify target neurons, and a second lead with stimulationelectrodes that replaces the first after target neuron identification.In some embodiments, the same lead can include both recording electrodesand stimulation electrodes or electrodes can be used for both recordingand stimulation.

FIG. 1 illustrates one embodiment of a device 100 for electricalstimulation (for example, brain or spinal cord stimulation). The deviceincludes a lead 110, a plurality of electrodes 125 disposed at leastpartially about a circumference of the lead 110, a plurality ofterminals 135, a connector 132 for connection of the electrodes to acontrol module, and a stylet 140 for assisting in insertion andpositioning of the lead in the patient's brain. The stylet 140 can bemade of a rigid material. Examples of suitable materials for the styletinclude, but are not limited to, tungsten, stainless steel, and plastic.The stylet 140 may have a handle 150 to assist insertion into the lead110, as well as rotation of the stylet 140 and lead 110. The connector132 fits over a proximal end of the lead 110, preferably after removalof the stylet 140. The connector 132 can be part of a control module 133or can be part of an optional lead extension 131 that is coupled to thecontrol module.

The control module 133 can be an implantable pulse generator that can beimplanted into a patient's body, for example, below the patient'sclavicle area. The control module can have eight stimulation channelswhich may be independently programmable to control the magnitude of thecurrent stimulus from each channel. In some cases the control module canhave more or fewer than eight stimulation channels (e.g., 4-, 6-, 16-,32-, or more stimulation channels). The control module can have one,two, three, four, or more connector ports, for receiving the pluralityof terminals 135 at the proximal end of the lead 110. Examples ofcontrol modules are described in the references cited above.

In one example of operation, access to the desired position in the braincan be accomplished by drilling a hole in the patient's skull or craniumwith a cranial drill (commonly referred to as a burr), and coagulatingand incising the dura mater, or brain covering. The lead 110 can beinserted into the cranium and brain tissue with the assistance of thestylet 140. The lead 110 can be guided to the target location within thebrain using, for example, a stereotactic frame and a microdrive motorsystem. In some embodiments, the microdrive motor system can be fully orpartially automatic. The microdrive motor system may be configured toperform one or more the following actions (alone or in combination):insert the lead 110, retract the lead 110, or rotate the lead 110.

In some embodiments, measurement devices coupled to the muscles or othertissues stimulated by the target neurons, or a unit responsive to thepatient or clinician, can be coupled to the control module or microdrivemotor system. The measurement device, user, or clinician can indicate aresponse by the target muscles or other tissues to the stimulation orrecording electrode(s) to further identify the target neurons andfacilitate positioning of the stimulation electrode(s). For example, ifthe target neurons are directed to a muscle experiencing tremors, ameasurement device can be used to observe the muscle and indicatechanges in tremor frequency or amplitude in response to stimulation ofneurons. Alternatively, the patient or clinician can observe the muscleand provide feedback.

The lead 110 for deep brain stimulation can include stimulationelectrodes, recording electrodes, or both. In at least some embodiments,the lead 110 is rotatable so that the stimulation electrodes can bealigned with the target neurons after the neurons have been locatedusing the recording electrodes.

Stimulation electrodes may be disposed on the circumference of the lead110 to stimulate the target neurons. Stimulation electrodes may bering-shaped so that current projects from each electrode equally inevery direction from the position of the electrode along a length of thelead 110. Ring electrodes typically do not enable stimulus current to bedirected from only a limited angular range around of the lead. Segmentedelectrodes, however, can be used to direct stimulation energy to aselected angular range around the lead. When segmented electrodes areused in conjunction with an implantable control module that deliversconstant current stimulus, current steering can be achieved to moreprecisely deliver the stimulus to a position around an axis of the lead(i.e., radial positioning around the axis of the lead).

To achieve current steering, segmented electrodes can be utilized inaddition to, or as an alternative to, ring electrodes. Though thefollowing description discusses stimulation electrodes, it will beunderstood that all configurations of the stimulation electrodesdiscussed may be utilized in arranging recording electrodes as well. Alead that includes segmented electrodes can be referred to as adirectional lead because the segmented electrodes can be used to directstimulation along a particular direction or range of directions.

The lead 100 includes a lead body 110, one or more optional ringelectrodes 120, and a plurality of sets of segmented electrodes 130. Thelead body 110 can be formed of a biocompatible, non-conducting materialsuch as, for example, a polymeric material. Suitable polymeric materialsinclude, but are not limited to, silicone, polyurethane, polyurea,polyurethane-urea, polyethylene, or the like. Once implanted in thebody, the lead 100 may be in contact with body tissue for extendedperiods of time. In at least some embodiments, the lead 100 has across-sectional diameter of no more than 1.5 mm and may be in the rangeof 0.5 to 1.5 mm. In at least some embodiments, the lead 100 has alength of at least 10 cm and the length of the lead 100 may be in therange of 10 to 70 cm.

The electrodes can be made using a metal, alloy, conductive oxide, orany other suitable conductive biocompatible material. Examples ofsuitable materials include, but are not limited to, platinum, platinumiridium alloy, iridium, titanium, tungsten, palladium, palladiumrhodium, or the like. Preferably, the electrodes are made of a materialthat is biocompatible and does not substantially corrode under expectedoperating conditions in the operating environment for the expectedduration of use.

Each of the electrodes can either be used or unused (OFF). When theelectrode is used, the electrode can be used as an anode or cathode andcarry anodic or cathodic current. In some instances, an electrode mightbe an anode for a period of time and a cathode for a period of time.

Stimulation electrodes in the form of ring electrodes 120 can bedisposed on any part of the lead body 110, usually near a distal end ofthe lead 100. In FIG. 1, the lead 100 includes two ring electrodes 120.Any number of ring electrodes 120 can be disposed along the length ofthe lead body 110 including, for example, one, two three, four, five,six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen,fifteen, sixteen or more ring electrodes 120. It will be understood thatany number of ring electrodes can be disposed along the length of thelead body 110. In some embodiments, the ring electrodes 120 aresubstantially cylindrical and wrap around the entire circumference ofthe lead body 110. In some embodiments, the outer diameters of the ringelectrodes 120 are substantially equal to the outer diameter of the leadbody 110. The length of the ring electrodes 120 may vary according tothe desired treatment and the location of the target neurons. In someembodiments the length of the ring electrodes 120 are less than or equalto the diameters of the ring electrodes 120. In other embodiments, thelengths of the ring electrodes 120 are greater than the diameters of thering electrodes 120. The distal-most ring electrode 120 may be a tipelectrode (see, e.g., tip electrode 320 a of FIG. 3E) which covers most,or all, of the distal tip of the lead.

Deep brain stimulation leads may include one or more sets of segmentedelectrodes. Segmented electrodes may provide for superior currentsteering than ring electrodes because target structures in deep brainstimulation are not typically symmetric about the axis of the distalelectrode array. Instead, a target may be located on one side of a planerunning through the axis of the lead. Through the use of a radiallysegmented electrode array (“RSEA”), current steering can be performednot only along a length of the lead but also around a circumference ofthe lead. This provides precise three-dimensional targeting and deliveryof the current stimulus to neural target tissue, while potentiallyavoiding stimulation of other tissue. Examples of leads with segmentedelectrodes include U.S. Patent Applications Publication Nos.2010/0268298; 2011/0005069; 2011/0078900; 2011/0130803; 2011/0130816;2011/0130817; 2011/0130818; 2011/0078900; 2011/0238129; 2011/0313500;2012/0016378; 2012/0046710; 2012/0071949; 2012/0165911; 2012/197375;2012/0203316; 2012/0203320; 2012/0203321; 2013/0197602; 2013/0261684;2013/0325091; 2013/0317587; 2014/0039587; 2014/0353001; 2014/0358209;2014/0358210; 2015/0018915; 2015/0021817; 2015/0045864; 2015/0021817;2015/0066120; 2013/0197424; 2015/0151113; 2014/0358207; and U.S. Pat.No. 8,483,237, all of which are incorporated herein by reference intheir entireties. Examples of leads with tip electrodes include at leastsome of the previously cited references, as well as U.S. PatentApplications Publication Nos. 2014/0296953 and 2014/0343647, all ofwhich are incorporated herein by reference in their entireties.

The lead 100 is shown having a plurality of segmented electrodes 130.Any number of segmented electrodes 130 may be disposed on the lead body110 including, for example, one, two three, four, five, six, seven,eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteenor more segmented electrodes 130. It will be understood that any numberof segmented electrodes 130 may be disposed along the length of the leadbody 110. A segmented electrode 130 typically extends only 75%, 67%,60%, 50%, 40%, 33%, 25%, 20%, 17%, 15%, or less around the circumferenceof the lead.

The segmented electrodes 130 may be grouped into sets of segmentedelectrodes, where each set is disposed around a circumference of thelead 100 at a particular longitudinal portion of the lead 100. The lead100 may have any number segmented electrodes 130 in a given set ofsegmented electrodes. The lead 100 may have one, two, three, four, five,six, seven, eight, or more segmented electrodes 130 in a given set. Inat least some embodiments, each set of segmented electrodes 130 of thelead 100 contains the same number of segmented electrodes 130. Thesegmented electrodes 130 disposed on the lead 100 may include adifferent number of electrodes than at least one other set of segmentedelectrodes 130 disposed on the lead 100.

The segmented electrodes 130 may vary in size and shape. In someembodiments, the segmented electrodes 130 are all of the same size,shape, diameter, width or area or any combination thereof. In someembodiments, the segmented electrodes 130 of each circumferential set(or even all segmented electrodes disposed on the lead 100) may beidentical in size and shape.

Each set of segmented electrodes 130 may be disposed around thecircumference of the lead body 110 to form a substantially cylindricalshape around the lead body 110. The spacing between individualelectrodes of a given set of the segmented electrodes may be the same,or different from, the spacing between individual electrodes of anotherset of segmented electrodes on the lead 100. In at least someembodiments, equal spaces, gaps or cutouts are disposed between eachsegmented electrode 130 around the circumference of the lead body 110.In other embodiments, the spaces, gaps or cutouts between the segmentedelectrodes 130 may differ in size or shape. In other embodiments, thespaces, gaps, or cutouts between segmented electrodes 130 may be uniformfor a particular set of the segmented electrodes 130, or for all sets ofthe segmented electrodes 130. The sets of segmented electrodes 130 maybe positioned in irregular or regular intervals along a length the leadbody 110.

Conductor wires that attach to the ring electrodes 120 or segmentedelectrodes 130 extend along the lead body 110. These conductor wires mayextend through the material of the lead 100 or along one or more lumensdefined by the lead 100, or both. The conductor wires couple theelectrodes 120, 130 to the terminals 135.

When the lead 100 includes both ring electrodes 120 and segmentedelectrodes 130, the ring electrodes 120 and the segmented electrodes 130may be arranged in any suitable configuration. For example, when thelead 100 includes two ring electrodes 120 and two sets of segmentedelectrodes 130, the ring electrodes 120 can flank the two sets ofsegmented electrodes 130 (see e.g., FIGS. 1, 3A, and 3E-3H—ringelectrodes 320 and segmented electrode 330). Alternately, the two setsof ring electrodes 120 can be disposed proximal to the two sets ofsegmented electrodes 130 (see e.g., FIG. 3C—ring electrodes 320 andsegmented electrode 330), or the two sets of ring electrodes 120 can bedisposed distal to the two sets of segmented electrodes 130 (see e.g.,FIG. 3D—ring electrodes 320 and segmented electrode 330). One of thering electrodes can be a tip electrode (see, tip electrode 320 a ofFIGS. 3E and 3G). It will be understood that other configurations arepossible as well (e.g., alternating ring and segmented electrodes, orthe like).

By varying the location of the segmented electrodes 130, differentcoverage of the target neurons may be selected. For example, theelectrode arrangement of FIG. 3C may be useful if the physiciananticipates that the neural target will be closer to a distal tip of thelead body 110, while the electrode arrangement of FIG. 3D may be usefulif the physician anticipates that the neural target will be closer to aproximal end of the lead body 110.

Any combination of ring electrodes 120 and segmented electrodes 130 maybe disposed on the lead 100. For example, the lead may include a firstring electrode 120, two sets of segmented electrodes; each set formed offour segmented electrodes 130, and a final ring electrode 120 at the endof the lead. This configuration may simply be referred to as a 1-4-4-1configuration (FIGS. 3A and 3E—ring electrodes 320 and segmentedelectrode 330). It may be useful to refer to the electrodes with thisshorthand notation. Thus, the embodiment of FIG. 3C may be referred toas a 1-1-4-4 configuration, while the embodiment of FIG. 3D may bereferred to as a 4-4-1-1 configuration. The embodiments of FIGS. 3F, 3G,and 3H can be referred to as a 1-3-3-1 configuration. Other electrodeconfigurations include, for example, a 2-2-2-2 configuration, where foursets of segmented electrodes are disposed on the lead, and a 4-4configuration, where two sets of segmented electrodes, each having foursegmented electrodes 130 are disposed on the lead. The 1-3-3-1 electrodeconfiguration of FIGS. 3F, 3G, and 3H has two sets of segmentedelectrodes, each set containing three electrodes disposed around thecircumference of the lead, flanked by two ring electrodes (FIGS. 3F and3H) or a ring electrode and a tip electrode (FIG. 3G). In someembodiments, the lead includes 16 electrodes. Possible configurationsfor a 16-electrode lead include, but are not limited to 4-4-4-4; 8-8;3-3-3-3-3-1 (and all rearrangements of this configuration); and2-2-2-2-2-2-2-2.

FIG. 2 is a schematic diagram to illustrate radial current steeringalong various electrode levels along the length of the lead 200. Whileconventional lead configurations with ring electrodes are only able tosteer current along the length of the lead (the z-axis), the segmentedelectrode configuration is capable of steering current in the x-axis,y-axis as well as the z-axis. Thus, the centroid of stimulation may besteered in any direction in the three-dimensional space surrounding thelead 200. In some embodiments, the radial distance, r, and the angle θaround the circumference of the lead 200 may be dictated by thepercentage of anodic current (recognizing that stimulation predominantlyoccurs near the cathode, although strong anodes may cause stimulation aswell) introduced to each electrode. In at least some embodiments, theconfiguration of anodes and cathodes along the segmented electrodesallows the centroid of stimulation to be shifted to a variety ofdifferent locations along the lead 200.

As can be appreciated from FIG. 2, the centroid of stimulation can beshifted at each level along the length of the lead 200. The use ofmultiple sets of segmented electrodes at different levels along thelength of the lead allows for three-dimensional current steering. Insome embodiments, the sets of segmented electrodes are shiftedcollectively (i.e., the centroid of simulation is similar at each levelalong the length of the lead). In at least some other embodiments, eachset of segmented electrodes is controlled independently. Each set ofsegmented electrodes may contain two, three, four, five, six, seven,eight or more segmented electrodes. It will be understood that differentstimulation profiles may be produced by varying the number of segmentedelectrodes at each level. For example, when each set of segmentedelectrodes includes only two segmented electrodes, uniformly distributedgaps (inability to stimulate selectively) may be formed in thestimulation profile. In some embodiments, at least three segmentedelectrodes 230 in a set are utilized to allow for true 360° selectivity.

As previously indicated, the foregoing configurations may also be usedwhile utilizing recording electrodes. In some embodiments, measurementdevices coupled to the muscles or other tissues stimulated by the targetneurons or a unit responsive to the patient or clinician can be coupledto the control module or microdrive motor system. The measurementdevice, user, or clinician can indicate a response by the target musclesor other tissues to the stimulation or recording electrodes to furtheridentify the target neurons and facilitate positioning of thestimulation electrodes. For example, if the target neurons are directedto a muscle experiencing tremors, a measurement device can be used toobserve the muscle and indicate changes in tremor frequency or amplitudein response to stimulation of neurons. Alternatively, the patient orclinician may observe the muscle and provide feedback.

The reliability and durability of the lead will depend heavily on thedesign and method of manufacture. Fabrication techniques discussed belowprovide methods that can produce manufacturable and reliable leads.

Returning to FIG. 1, when the lead 100 includes a plurality of sets ofsegmented electrodes 130, it may be desirable to form the lead 100 suchthat corresponding electrodes of different sets of segmented electrodes130 are radially aligned with one another along the length of the lead100 (see e.g., the segmented electrodes 130 shown in FIG. 1). Radialalignment between corresponding electrodes of different sets ofsegmented electrodes 130 along the length of the lead 100 may reduceuncertainty as to the location or orientation between correspondingsegmented electrodes of different sets of segmented electrodes.Accordingly, it may be beneficial to form electrode arrays such thatcorresponding electrodes of different sets of segmented electrodes alongthe length of the lead 100 are radially aligned with one another and donot radially shift in relation to one another during manufacturing ofthe lead 100.

In other embodiments, individual electrodes in the two sets of segmentedelectrodes 130 are staggered (see, FIG. 3B) relative to one anotheralong the length of the lead body 110. In some cases, the staggeredpositioning of corresponding electrodes of different sets of segmentedelectrodes along the length of the lead 100 may be designed for aspecific application.

Segmented electrodes can be used to tailor the stimulation region sothat, instead of stimulating tissue around the circumference of the leadas would be achieved using a ring electrode, the stimulation region canbe directionally targeted. In some instances, it is desirable to targeta parallelepiped (or slab) region 250 that contains the electrodes ofthe lead 200, as illustrated in FIG. 2. One arrangement for directing astimulation field into a parallelepiped region uses segmented electrodesdisposed on opposite sides of a lead.

FIGS. 3A-3H illustrate leads 300 with segmented electrodes 330, optionalring electrodes 320 or tip electrodes 320 a, and a lead body 310. Thesets of segmented electrodes 330 each include either two (FIG. 3B),three (FIGS. 3E-3H), or four (FIGS. 3A, 3C, and 3D) or any other numberof segmented electrodes including, for example, three, five, six, ormore. The sets of segmented electrodes 330 can be aligned with eachother (FIGS. 3A-3G) or staggered (FIG. 3H)

Any other suitable arrangements of segmented electrodes can be used. Asan example, arrangements in which segmented electrodes are arrangedhelically with respect to each other. One embodiment includes a doublehelix.

In at least some instances, a treating physician may wish to tailor thestimulation parameters (such as which one or more of the stimulatingelectrode contacts to use, the stimulation pulse amplitude (such ascurrent or voltage amplitude depending on the stimulator being used) thestimulation pulse width, the stimulation frequency, or the like or anycombination thereof) for a particular patient to improve theeffectiveness of the therapy. Electrical stimulation systems can providean interface that facilitates parameter selections. Examples of suchsystems and interfaces can be found in, for example, U.S. patentapplication Ser. Nos. 12/454,330; 12/454,312; 12/454,340; 12/454,3431;and 12/454,314 and U.S. Patent Application Publication No. 2014/0277284,all of which are incorporated herein by reference in their entireties.

Conventional electrical stimulation (such as deep brain or spinal cordstimulation) can include a programming procedure that is often performedin an initial session and, in at least some instances, at latersessions. The procedure can involve, for example, testing different setsof stimulation parameters (which can include variations in theelectrodes that are selected as well as different electrical parameterssuch as amplitude, duration, pulse frequency, and the like) andannotating when there is a beneficial therapeutic effect or an unwantedside effect. In at least some embodiments, the clinician performs amonopolar review testing each electrode individually and recordingtherapeutic/beneficial effects and side effects for each electrode onthe lead corresponding to different values of the stimulation amplitudeor other stimulation parameters. The clinician may also perform bipolaror multipolar reviews using two or more electrodes.

In contrast to these conventional methods, automated steering algorithmsand systems can enable or enhance stimulation field shaping to generatecustomized, user-defined targets rather than relying on manualprogramming or limiting users to pre-set configurations. Such algorithmsand systems may provide greater ease of use and flexibility and mayenable or enhance specific targeting of stimulation therapy. The terms“stimulation field map” (SFM) and “volume of activation” (VOA) are oftenused to designate an estimated region of tissue that will be stimulatedfor a particular set of stimulation parameters.

As described herein, a clinician or other individual can specify adesired virtual electrode or stimulation target. An automated system canidentify stimulation parameters for the actual electrodes on the leadthat attempt to fit this virtual electrode or stimulation target. Inmany instances, the fit is not exact and, therefore, it is useful toprovide instructions regarding finding a best or desirable fit. Thesystems and methods described herein take into account user-selectedweighting of regions around the lead. In many instances, the field nearthe electrodes is more important than the field further from theelectrodes. Accordingly, a user can weight the regions around the leadbased on importance of that region to the overall stimulation. In atleast some embodiments, the user may also exclude one or more of theelectrodes of the lead in the determination of stimulation parameters orset one or more of the electrodes at a desired amplitude.

FIG. 4 presents in a flowchart one embodiment of a method of determiningstimulation parameters for an electrical stimulation program. In thedescription below, the amplitude and polarity of the stimulation at oneor more of the electrodes are determined using the method, but it willbe understood that other parameters, such as pulse width or pulseduration, may also be varied for individual electrodes or one or moregroups of electrodes. For example, the lead can be any of the leadsillustrated in the Figures or any other suitable lead with multipleelectrodes in any suitable arrangement. Also, although the electrodesare indicated as disposed on a single lead, it will be understood thatelectrodes from multiple leads can be used. Furthermore, it at leastsome embodiments, one or more electrodes may be provided on the housingof the control module. For example, the housing may have an electrodewhich acts as a cathode or anode.

In step 402, the user determines a target. The target can be, forexample, a virtual electrode, a center of stimulation, or a targetstimulation field. In at least some embodiments, a user interface can beprovided with a representation of, for example, the distal portion ofthe lead and the available electrodes on that portion (or any othersuitable representation of the lead or portion of the lead or portion ofthe anatomy in which the lead is implanted or to be implanted). The userinterface may permit the user to select, draw, or otherwise indicate acenter of stimulation, virtual electrode, or target stimulation field.

A “virtual electrode” is an electrode that is designated by the userwhich may or may not correspond to an actual electrode on the lead. FIG.5A illustrates user interface with one example of a representation of aset of lead electrodes with a ring electrode 520 and a tip electrode 520a separated by two sets with three segmented electrodes 530 each (i.e.,the arrangement illustrated in FIG. 3G). In the illustrated embodiment,the user has selected or drawn a virtual electrode 535 that extendsbetween and overlaps the two sets of segmented electrodes 530 andextends between and overlaps two segmented electrodes in each set. FIG.5B illustrates another user interface with an example of arepresentation of three segmented electrodes 530 in a lateralcross-section with a virtual electrode 535 selected or drawn relative tothe segmented electrodes. It will be understood that other methods orarrangement for selecting, drawing, or otherwise indicating a center ofstimulation, virtual electrode, or target stimulation field can be used.

If a center of stimulation or virtual electrode or the like is selected,the system determines a target stimulation field based on thatselection. The target stimulation field can be determined using anysuitable method including, for example, estimating a field generatedfrom the virtual electrode or from an electrode disposed at a point ofthe lead nearest the selected center of stimulation. In otherembodiments, a stimulation field model (SFM) or volume of activation(VOA) can be used to determine the target stimulation field. Anysuitable method for determining the SFM or VOA can be used includingthose described in, for example, U.S. Pat. Nos. 8,326,433; 8,675,945;8,831,731; 8,849,632; and 8,958,615; U.S. Patent ApplicationPublications Nos. 2009/0287272; 2009/0287273; 2012/0314924;2013/0116744; 2014/0122379; and 2015/0066111; and U.S. ProvisionalPatent Application Ser. No. 62/030,655, all of which are incorporatedherein by reference in their entirety.

In optional step 404, parameters of one or more of the electrodes can beset. For example, one or more of the electrodes may be set to zeroamplitude or to a fixed amplitude. Additionally or alternatively,parameters such as pulse width or maximum amplitude or total amplitudemay be set. In at least some embodiments, one or more of theseparameters may be predefined.

In step 406, the relative weights for one or more spatial regions aroundthe lead is selected. The objective of the procedure is to determinestimulation parameters for the existing electrodes that willapproximately generate the target stimulation field. The stimulationfield generated by the stimulation parameters will not be exactly thesame as the target stimulation field, so at least some conventionalsystems select stimulation parameters that minimize the differencebetween the generated stimulation field and the target stimulationfield. In contrast, the present methods and systems recognize thatdeviation from the target stimulation field in some spatial regions maybe more significant than the same deviation in other areas. For example,in some instances, conformance of the generated stimulation field to thetarget stimulation field near the lead is more important thatconformance far away from the lead. The present methods and systemspermit the user to modify the weighting of the deviations from thetarget stimulation field for different spatial regions around the lead.In at least some embodiments, the user may also be allowed to definespatial regions around the lead and then select weighting for thosespatial regions. In at least some embodiments, the spatial regions canbe predefined. In at least some embodiments, the weights of thedifferent regions may be predefined or predetermined. Optionally, thesepredefined or predetermined weights may be modifiable by the user.

FIG. 6A illustrates one embodiment of a user interface 650 with arepresentation 600 of the lead or electrodes and six regions 640 labeled“1” through “6”. (For clarity of illustration, the portion of therepresentation 600 in regions “1” and “2” has been deleted so that thoseregions can be clearly identified. Compare with FIG. 7.) In thisembodiment, regions “1” and “2” are near the lead, regions “3” and “4”are at medium distance from the lead, and regions “5” and “6” are at afar distance from the lead. The user interface 650 also includes aselection area 652 for selecting the weighting for the regions 640.

FIG. 6B illustrates the user interface 650 with a “High” weightingselected for regions “1” and “2”, a “Medium” weighting selected forregions “3” and “4”, and a “Low” weighting selected for regions “5” and“6”. FIG. 6B also illustrates a selected center of stimulation 642 and aregion of expected stimulation 644 based on that center of stimulation.In addition, the regions 650 have been graphically modified based on theselected weighting. Such graphical modifications can be, for example,differences in color, shading, cross-hatching, or any other suitablevisible indicator. This graphical modification of the regions isoptional, but can be helpful for visualization of the weighting.

FIG. 6C illustrates another user interface 650 with a “High” weightingselected for region “3”, a “Medium” weighting selected for regions “1”,“2”, and “4”, and a “Low” weighting selected for regions “5” and “6”.FIG. 6C also illustrates a region of expected stimulation 644.

The illustrated embodiments use three categories of weighting: “High”,“Medium”, and “Low”. This categorization is a non-numerical qualitativedescription of the weighting. Other types of categorization can be usedincluding, but not limited to, numerical categorization or qualitativenumerical descriptions (where the numbers are not necessarily indicativeof the weighting value, but rather are intended to convey a relativeimportance of the region.) In some embodiments, the user may enter aweighting, select a weighting from a menu or other list, or use a scaleor slider to select a weighting. The scale or slider may be a numeric ornon-numeric scale or slider. In some embodiments, the weight can also beselected to be zero or “None” or the like. In some embodiments, a weightor designation can also be selected to indicate that the region is to beavoided (for example, that the generated stimulation field should avoidor minimize extension into that regions.)

The illustrated embodiment utilizes three categories, but it will berecognized that more or fewer weighting categories can also be usedincluding, but not limited to, two, three, four, five, six, eight, ten,or twelve or more categories. In at least some embodiments, eachweighting category can be associated with a numerical value, w_(i),where i is an integer representing the category. For example, “High” canhave a numerical value of 5, “Medium” can have a numerical value of 3,and “Low” can have a numerical value of 1.

In the illustrated embodiments, the generated stimulation field based onthe stimulation parameters that will be determined will be more preciseand refined, relative to the target stimulation field, in regions with“High” weighting. In regions with “Low” weighting, conformance of thegenerated stimulation field with the target stimulation field will belower and assigning regions to “Low” may also improve calculation speedand efficiency.

In optional step 408, the user may be permitted to select from two ormore different weighting models. In other embodiments, one of the modelsmay be automatically used or the system or method can employ multiplemodels and combine the results or present several results for selectionor use by the user or system.

One example of a weighting model uses a uniform grid of points 660arranged over the regions 640, as illustrated in FIG. 7. The stimulationfield potential (φ_(actual)) at each point is determined based on a setof stimulation parameters and then compared to the target stimulationfield potential (φ_(target)) at that point. The stimulation fieldpotential can be described by the equation: Ĵ=A⁻¹φ_(actual) where Ĵ is aset of electrode amplitudes or relative weightings (i.e., the set ofelectrodes selected to produce the target stimulation field potential)and A are the extracellular potentials generated by unit amplitudes. Anerror (ε) is defined as ε=|AĴ−φ_(target)|. The error will depend on thenumber of points within each region. In at least some embodiments, eachregion will be assigned the same number of points, as illustrated inFIG. 7. The error term arising from each region, however, will beweighted differently according to the selected weights which means thatthe contribution of a region to the overall error can be enhanced orreduced by selection of the weight.

This inverse modeling technique then seeks to minimize or reduce theerror between potentials at all points generated by the actualelectrodes (φ_(actual)) and the target stimulation field potential(φ_(target)). As an example, one embodiment has two regions: near field(nf) and far field (ff). Associated with these fields are a near fieldweight (w_(nf)) and a far field weight (w_(ff)). The error (ε) has aweighted near field component (w_(nf)·ε) and a far field component(w_(ff)·ε) whereε=|AĴ−φ _(target)|w _(nf) ·ε=w _(nf) ·|A _(nf) Ĵ−φ _(target,nf)|w _(ff) ·ε=w _(ff) ·|A _(ff) Ĵ−φ _(target,ff)|.

If the number of near region and far region observational points are thesame, using the subadditivity property of absolute values |a+b|≤|a|+|b|and assuming the “worst case” where |a+b| equal to |a|+|b|) then:ε_(total) =w _(nf)·ε_(nf) +w _(ff)·ε_(ff) =|w _(nf) ·A _(nf) Ĵ−w_(nf)·φ_(target,nf) +w _(ff) ·A _(ff) Ĵ−w _(ff)·φ_(target,ff)|ε_(total) =w _(nf)·ε_(nf) +w _(ff)·ε_(ff)=|(w _(nf) ·A _(nf) +w _(ff) ·A_(ff)){circumflex over (J)}−(w _(nf)·φ_(target,nf) +w_(ff)·φ_(target,ff))|

The total error is then minimized or reduced by solving for Ĵ such that(w _(nf) ·A _(nf) +w _(ff) ·A _(ff)){circumflex over (J)}=(w_(nf)·φ_(target,nf) +w _(ff)·φ_(target,ff))

In an alternative model, instead of using the same number of points ineach region, the weighting is accomplished by changing the relativenumber of points in each region, as illustrated in FIG. 8. In theillustrated embodiment, regions “1” and “2” (see, FIG. 6A) have the samenumber of points, regions “3” and “4” have only two thirds of the pointsof regions “1” and “2”, and regions “5” and “6” have only one third thepoints of regions “1” and “2”. In this model, the error value is simplythe sum of differences between the actual stimulation field and targetstimulation field at each point. The weighting in this model isaccounted for by the difference in number of points for each region. Inthis model, regions with more points will produce more contributions tothe error term and, therefore, minimizing or reducing the error termwill result in closer adherence of the generated stimulation field tothe target stimulation field in the regions with more points. This modelmay be more computationally efficient, but will have lower spatialresolution than the preceding model.

In at least some embodiments, the user interface can allow the user todefine resolution of point(s) (e.g., the number of points in each regionor in the highest weight regions) according to consideration ofefficiency or computational time. In at least some embodiments, the userinterface may allow the user to toggle between highest resolution (firstmodel) and “efficiency” (second model) modes. These models aregeneralizable to all electrode geometries, any number of regions, andany selection of weights for those regions. It will also be recognizedthat any other suitable model that incorporates the selected weights forthe regions can be used. It will also be recognized that each model mayalso incorporate one or more constraints on the model, such as, forexample, the maximum amplitude for each electrode, the total maximumanodic or cathodic amplitude over all electrodes, the presence oramplitude for an electrode on the housing of the control module, or thelike or any combination thereof.

In step 410, electrode parameters, such which electrodes are to be used,electrode polarity (e.g., anode or cathode), electrode amplitude, or thelike or any combination thereof, are determined using a weighting model,such as one of the models described above. In step 412, the determinedset of stimulation parameters are output to the user. In someembodiments, these parameters may be output to (for example, transmittedor otherwise conveyed to) the control module for delivery of stimulationto the patient based on these parameters. In some embodiments, the userinterface may display the parameters. In some embodiments, the userinterface may display the generated stimulation field that is estimatedto be obtained using these parameters. The user interface may alsodisplay the target stimulation field and may optionally identifydifferences between the generated stimulation field and the targetstimulation field. The user may also display the target stimulationfield in relation to a model of the distal end of the lead and theelectrodes of the lead, similar to the interface illustrated, forexample, in FIGS. 6A-6C.

As described above, there may be situations when it is desirable thatone or more of the electrodes are set to an off position or have a fixedamplitude. In one embodiment of a user interface 950, an electrode 930can be selected and excluded using a control on the user interface, asillustrated in FIG. 9. In some embodiments, a side-menu 972 may bedisplayed asking the user to indicate a reason for excluding theelectrode. Examples of reasons can include, but are not limited to, theelectrode being a sensing electrode only, a diagnostic fault, a desireto avoid stimulation near that electrode, or a desire to discount oravoid consideration of a region near the electrode. The procedureillustrated in FIG. 4 can proceed with the excluded electrode set to 0.In some embodiments, the system may also disallow certain conditions.For example, the system may not allow specification of more sensingelectrodes than there are sensor inputs in the device. The system mayalso warn or disallow drawing of a virtual electrode whose domain isonly within the excluded electrode(s). In some embodiments, instead ofsetting a particular electrode to zero amplitude, the weighting of aregion adjacent the electrode can be set to zero.

In at least some embodiments, an electrode 1030 a, 1030 b can beselected and fixed at a value using a control on the user interface1050, as illustrated in FIG. 10. Values at which electrodes are fixedmay be system-specified or entered by the user. The procedureillustrated in FIG. 4 can proceed with the selected electrode set to thefixed value. In at least some embodiments, a warning or error may beindicated by the system in the event of certain occurrences (forexample, a virtual electrode falling fully within fixed electrodes,amplitudes exceeding tolerances, previously excluded electrode beingfixed at nonzero value.

FIG. 11 illustrates one embodiment of a system for practicing theinvention. The system can include a computer 1100 or any other similardevice that includes a processor 1102 and a memory 1104, a display 1106,an input device 1108, and, optionally, the electrical stimulation system1112.

The computer 1100 can be a laptop computer, desktop computer, tablet,mobile device, smartphone or other devices that can run applications orprograms, or any other suitable device for processing information andfor presenting a user interface (such as the user interfaces of FIGS.5A, 5B, 6A-6C, 9, and 10). The computer can be, for example, a clinicianor remote programmer for the electrical stimulation system 1112. Thecomputer 1100 can be local to the user or can include components thatare non-local to the computer including one or both of the processor1102 or memory 1104 (or portions thereof). For example, in someembodiments, the user may operate a terminal that is connected to anon-local computer. In other embodiments, the memory can be non-local tothe user.

The computer 1100 can utilize any suitable processor 1102 including oneor more hardware processors that may be local to the user or non-localto the user or other components of the computer. The processor 1102 isconfigured to execute instructions provided to the processor, asdescribed below.

Any suitable memory 1104 can be used for the computer 1102. The memory1104 illustrates a type of computer-readable media, namelycomputer-readable storage media. Computer-readable storage media mayinclude, but is not limited to, nonvolatile, non-transitory, removable,and non-removable media implemented in any method or technology forstorage of information, such as computer readable instructions, datastructures, program modules, or other data. Examples ofcomputer-readable storage media include RAM, ROM, EEPROM, flash memory,or other memory technology, CD-ROM, digital versatile disks (“DVD”) orother optical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to store the desired information and which can be accessed by acomputer.

Communication methods provide another type of computer readable media;namely communication media. Communication media typically embodiescomputer-readable instructions, data structures, program modules, orother data in a modulated data signal such as a carrier wave, datasignal, or other transport mechanism and include any informationdelivery media. The terms “modulated data signal,” and “carrier-wavesignal” includes a signal that has one or more of its characteristicsset or changed in such a manner as to encode information, instructions,data, and the like, in the signal. By way of example, communicationmedia includes wired media such as twisted pair, coaxial cable, fiberoptics, wave guides, and other wired media and wireless media such asacoustic, RF, infrared, and other wireless media.

The display 1106 can be any suitable display device, such as a monitor,screen, display, or the like, and can include a printer. The inputdevice 1108 can be, for example, a keyboard, mouse, touch screen, trackball, joystick, voice recognition system, or any combination thereof, orthe like and can be used by the user to interact with a user interfaceor clinical effects map.

The electrical stimulation system 1112 can include, for example, acontrol module 1114 (for example, an implantable pulse generator) and alead 1116 (for example, the lead illustrated in FIG. 1.) The electricalstimulation system 1112 may communicate with the computer 1100 through awired or wireless connection or, alternatively or additionally, a usercan provide information between the electrical stimulation system 1112and the computer 1100 using a computer-readable medium or by some othermechanism. In some embodiments, the computer 1100 may include part ofthe electrical stimulation system.

The methods and systems described herein may be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Accordingly, the methods and systemsdescribed herein may take the form of an entirely hardware embodiment,an entirely software embodiment or an embodiment combining software andhardware aspects. Systems referenced herein typically include memory andtypically include methods for communication with other devices includingmobile devices. Methods of communication can include both wired andwireless (e.g., RF, optical, or infrared) communications methods andsuch methods provide another type of computer readable media; namelycommunication media. Wired communication can include communication overa twisted pair, coaxial cable, fiber optics, wave guides, or the like,or any combination thereof. Wireless communication can include RF,infrared, acoustic, near field communication, Bluetooth™, or the like,or any combination thereof.

It will be understood that each block of the flowchart illustrations,and combinations of blocks in the flowchart illustrations and methodsdisclosed herein, can be implemented by computer program instructions.These program instructions may be provided to a processor to produce amachine, such that the instructions, which execute on the processor,create means for implementing the actions specified in the flowchartblock or blocks disclosed herein. The computer program instructions maybe executed by a processor to cause a series of operational steps to beperformed by the processor to produce a computer implemented process.The computer program instructions may also cause at least some of theoperational steps to be performed in parallel. Moreover, some of thesteps may also be performed across more than one processor, such asmight arise in a multi-processor computer system. In addition, one ormore processes may also be performed concurrently with other processes,or even in a different sequence than illustrated without departing fromthe scope or spirit of the invention.

The computer program instructions can be stored on any suitablecomputer-readable medium including, but not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (“DVD”) or other optical storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can be accessed by a computer.

The above specification, examples, and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A method for determining a set of stimulationparameters for an implantable stimulation device, the method comprising:receiving, by a computer processor, a stimulation target; determining,by the computer processor, a target stimulation field based on thestimulation target; requesting, from a user and by the computerprocessor, a weighting for each of a plurality of spatial regionsdefined relative to a lead comprising a plurality of electrodes,wherein, for at least one of the plurality of spatial regions,requesting the weighting is either a) requesting a numerical weightingor b) requesting a selection of a qualitative weighting from three ormore predefined qualitative weighting designations presented to the userby the computer processor, wherein each of the spatial represents aregion of tissue that can be directly stimulated by an electric fieldgenerated using the electrodes of the lead; receiving, in response tothe requesting, the weightings for each of the plurality of spatialregions, wherein the received weighting for at least one of the spatialregions is different from the received weighting for another one of thespatial regions; determining, by the computer processor and using theweightings for the plurality of spatial regions, a set of stimulationparameters to produce a generated stimulation field that approximatesthe target stimulation field; delivering the set of stimulationparameters to the implantable stimulation device; and stimulatingtissue, by the implantable stimulation device, using the set ofstimulation parameters.
 2. The method of claim 1, wherein the deliveringcomprises transmitting the set of stimulation parameters for receptionby the implantable stimulation device for delivery of electricalstimulation to a patient.
 3. The method of claim 1, wherein receivingthe weighting comprises assigning a default weighting to each spatialregion absent user input or selection of the weighting for that spatialregion.
 4. The method of claim 1, wherein the stimulation target is acenter of stimulation or a virtual electrode.
 5. The method of claim 4,wherein receiving a stimulation target comprises receiving, by thecomputer processor, a drawing of the virtual electrode on arepresentation of the lead.
 6. The method of claim 1, wherein steps ofreceiving a stimulation target and determining a target stimulationfield together comprise receiving, by the computer processor, auser-defined target stimulation field.
 7. The method of claim 6, whereinreceiving a user-defined target stimulation field comprises receiving,by the computer processor, a drawing of the user-defined targetstimulation field relative to a representation of the lead.
 8. Themethod of claim 1, further comprising receiving, by the computerprocessor, a user-definition of at least one of the spatial regionsrelative to a representation of the lead.
 9. The method of claim 1,wherein determining, using the weightings for the plurality of spatialregions, a set of stimulation parameters comprises minimizing, by thecomputer processor, a weighted error between the generated stimulationfield and the target stimulation field using the weightings for thespatial regions.
 10. The method of claim 9, further comprisingreceiving, by the computer processor, a selection of a model fordetermining the weighted error.
 11. The method of claim 1, furthercomprising displaying, on a display coupled to the computer processor,the target stimulation field and the generated stimulation field. 12.The method of claim 1, further comprising receiving, by the computerprocessor, a setting of at least one of the electrodes to a zerostimulation amplitude prior to the determining of the set of stimulationparameters and requiring, during the determination of the set ofstimulation parameters, that the at least one of the electrodes set tothe zero stimulation amplitude remains at the zero stimulationamplitude.
 13. The method of claim 12, further comprising upon receivingthe setting of the at least one of the electrodes to a zero amplitude,presenting, by the computer processor on a display, a menu ofuser-selectable reasons for the setting.
 14. The method of claim 1,further comprising receiving, by the computer processor, a setting of atleast one of the electrodes to a fixed stimulation amplitude prior tothe determining of the set of stimulation parameters and requiring,during the determination of the set of stimulation parameters, that theat least one of the electrodes set to the fixed stimulation amplituderemains at the fixed stimulation amplitude.
 15. The method of claim 1,wherein each of the predefined qualitative weighting designations is anon-numerical description of the weighting.
 16. The method of claim 1,wherein the spatial regions are pre-defined.
 17. The method of claim 1,wherein the spatial regions comprise at least one close region, at leastone medial region, and at least one far region, wherein the at least oneclose region is defined nearer the lead than the at least one medialregion which, in turn, is defined nearer the lead than the at least onefar region.
 18. A system for determining a set of stimulationparameters, the system comprising: an implantable stimulation device; adisplay; a memory; and a computer processor coupled to the display andthe memory and configured and arranged to perform the following actions:receive a stimulation target; determine a target stimulation field basedon the stimulation target; request, from a user, a weighting for aplurality of spatial regions defined relative to a lead comprising aplurality of electrodes, wherein, for at least one of the plurality ofspatial regions, requesting the weighting is either a) requesting anumerical weighting or b) requesting a selection of a qualitativeweighting from three or more predefined qualitative weightingdesignations presented to the user by the computer processor, whereineach of the spatial regions represents a region of tissue that can bedirectly stimulated by an electric field generated using the electrodesof the lead; receive, in response to the requesting, the weighting foreach of the plurality of spatial regions, wherein the received weightingfor at least one of the spatial regions is different from the receivedweighting for another one of the spatial regions; store the receivedweightings in the memory; determine, using the weightings for theplurality of spatial regions, a set of stimulation parameters to producea generated stimulation field that approximates the target stimulationfield; and direct delivery of the set of stimulation parameters to theimplantable stimulation device; wherein the system is configured andarranged for the implantable stimulation device to stimulate tissueusing the set of stimulation parameters from the computer processor. 19.The system of claim 18, wherein the implantable stimulation devicecomprises an implantable lead and an implantable control modulecoupleable to the implantable lead and configured and arranged toreceive the set of stimulation parameters from the computer processorand to deliver electrical stimulation to a patient using the implantablelead according to the set of stimulation parameters.